IPA: /ˈtiːdiəsli/
KK: /ˈtɛdɪəsli/
In a way that is boring and takes a long time, making you feel tired or annoyed.
The lecture went on tediously, making it hard for the students to stay focused.
Tediously → It is formed from "tedious" (from Latin *taediosus*, meaning tiresome or wearisome) and the suffix "-ly" (meaning in a manner of). The word "tediously" means in a manner that is tiresome or wearisome.
Think of something that is 'tiresome' ('tedious') and how it is done 'in a manner' ('-ly') that makes it feel long and boring.